EPITAXIAL CRYSTALLIZATION AND CRYSTALLINE POLYMORPHISM OF POLY(1-BUTENE) - FORM I'

The hexagonal form I' of poly(1-butene) is epitaxially crystallized on 4-bromo and 4-chlorobenzoic acids, on the potassium salts of these acids, and on the hemiacid, potassium hydrogen 4-chlorobenzoate. The contact plane in all cases is (11.0). In form I', the successive (11.0) planes contain, alternately, only left-hand or only right-hand helices. The observed epitaxies can therefore be differentiated according to the chirality of the helices in interaction with the substrate. Epitaxies are governed by a one-dimensional match which involves the interturn distance, i.e. the distance between successive outer helical paths. For less specific interactions, appropriate tilts of the helix axis helps achieve matching with the substrate lattice periodicities.